On Wed, Jun 22, 2011 at 02:06:13PM +0800, Aron Xu wrote:
> grub-pc will write MBR every time when triggered,

grub-pc does not use any dpkg triggers.

> and grub-pc-bin will not update grub entry after the kernel is
> updated. - It is weird when you have grub installed to an alternative
> place, then you upgrade a package and it write MBR regardless what you
> have chosen before.

grub-pc will only install to the device where it was previously
configured to install the MBR to, which is configured when you install
Debian or when you first install grub-pc. You can even configure it to
install nowhere, although this does require explicit confirmation.

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On Wed, Jun 22, 2011 at 02:26:31PM +0800, YunQiang Su wrote:
> But once upgrade Ubuntu, the MBR is taken place, and once then upgrade
> Debian, it's back.

'dpkg-reconfigure grub-pc' on the Ubuntu side, then - it's not that
complicated.

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On Wed, Jun 22, 2011 at 03:09:12PM +0800, YunQiang Su wrote:
> When installing, user will usually install grub in MBR or they have no
> choice to set it when install (install from LiveCD).

If you mean the Ubuntu live CD, IIRC it does have an option for this
although only when you're doing manual partitioning. But it's easy
enough to reconfigure later anyway, particularly for the sort of person
who has multiple operating systems installed.

> and I can not find out any necessity to run grub-install every time.

There is at present no guarantee of compatibility between older GRUB
images and newer generated configuration files. We try not to break
this gratuitously, but there have been some changes that affected
compatibility at various points in recent history, and we certainly
don't do very significant testing with older images (for instance, the
GRUB script "shell" gained several important new features in 1.99 and it
would not surprise me one bit to find autogenerated configuration files
taking advantage of these; I'm almost certain that current grub.cfg
files will not work with images from the 1.97 era).

If we simply left old images in place and never upgraded them, as you
suggest in #631224, then I guarantee you that other things would break;
it would be disastrously bad for users. We therefore try to upgrade
installed versions of GRUB to match the current installed package.

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On Wed, Jun 22, 2011 at 05:07:52AM +0100, Ben Hutchings wrote:
> On Wed, 2011-06-22 at 11:33 +0800, YunQiang Su wrote:
> > When update to grub-pc 1.99-8, it write my MBR, then I report a bug.
> >
> > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=631224
> >
> > and Colin Watson <cjwatson@debian.org> tell me that it's a new feature.

For the record, I told you no such thing, and I would like to correct
this misrepresentation. grub-pc has upgraded installed GRUB images
since well before I've been maintaining it, and definitely ever since
it's been the default in Debian.

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